Two different sized woofers with different sensitivity db in parallel?

[rebar]

Iv got a older 8 ohm 10" rockford fosgate rfp-1810 with 88 db sensitivity. I wanted to run it with a 8 ohm peavy 15" 1505 with 97.9 db sensitivity in parallel in different sealed sub-woofer box's until I saw the difference in sensitivity.

How much louder would the peavy be? And since I could place it further away in my ford E350 (all the way in back) would the 10" RF woofer always be overpowered by the 15" even if I placed it closer just behind the rear seats? Another option would be my second peavy 1505, but I don't have two fosgate 10" speakers.

Thanks

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[Full Tilt 10+ year member]

*Sigh*

Okay, the only thing you're going to hear from this forum is this: Don't run two different subwoofers in the same car audio application. It's just not good, usually doesn't sound right, and just seems odd. Different sizes, different brands, it's just a no-no.

Second, a driver's sensitivity doesn't really say one is going to be a louder speaker than the other. That is totally dependent on the acoustic environment of the vehicle. I really wish this hobby was as simple as 'put this one further away because it'll be louder, so they will sound the same,' but it's simply not.

If I had to decide what to do here, run the two drivers that are similar to each other. That'll give you the best sound here.

 

[RangerDangerV2 5,000+ posts]

good god... can people do any research before they ask questions? google is your friend....

 

[rebar]

*Sigh*If I had to decide what to do here, run the two drivers that are similar to each other. They'll give you the best sound here.

Thanks.. I will try the two 15's then.

good god... can people do any research before they ask questions? google is your friend....

I did, and found it was acceptable running two different sizes subs.. But the db rating being so far off is the only thing stopping me.

 

[Full Tilt 10+ year member]

I did, and found it was acceptable running two different sizes subs..

Where did you find that...?

 

[Chrispy 10+ year member]

I use my Peavey 15"s for midrange...

 

[rebar]

Where did you find that...?

Granted, its a guitar forum, but here

quote.. "you need to match not just the impedance of the speakers but the sensitivity ratings. IF you pair say a 92db speaker with a 100db speaker, you will not hear that 92db speaker because the higher efficiency speaker will be producing so much more volume."

I use my Peavey 15"s for midrange...

Yea I noticed the mids and higher volume, that's why I wanted to use the 10" but need to make enclosures to have any idea of the potential.

I have to add.. These speakers and materials are free and needing a home and Ill agree the 15's aren't the best choice unless I can remove the mids and boost the lows.

 

[Chrispy 10+ year member]

Yea I noticed the mids and higher volume, that's why I wanted to use the 10" but need to make enclosures to have any idea of the potential.

I have to add.. These speakers and materials are free and needing a home and Ill agree the 15's aren't the best choice unless I can remove the mids and boost the lows.

Of course you can by using a crossover. Are you not using any kind of crossover? My Peaveys are band passed from 80 Hz to 3500 Hz so they only play midbass/midrange. Whether you want bass or midrange out of them, they will need the proper crossover because playing full range, they will not sound good.

 

[Full Tilt 10+ year member]

Granted, its a guitar forum, but herequote.. "you need to match not just the impedance of the speakers but the sensitivity ratings. IF you pair say a 92db speaker with a 100db speaker, you will not hear that 92db speaker because the higher efficiency speaker will be producing so much more volume."

 

I'm sorry, but that information is straight up inaccurate.

 

[rebar]

I'm sorry, but that information is straight up inaccurate.

Thanks for the heads up.. You guys saved me from wasting a day of enclosure fab and frustration.

So my next problem is Iv got the older 8 ohm peavy 1505's They are not the latest 1505 DT8.. or 1505 KADT8 so I cant find the specs to design the sealed cabinet.

I cheated and used specs from the 1505 DT8 and came up with 2.64 cubic feet with this calc, but peavy didn't list the Qtc number so used the default .707 needed for a sealed cabinet calc.

I don't like using the specs for a speaker that's close, and also a default Qts number.. Two strikes..

Or is it that critical for a sealed enclosure? Because I found another person who used less than 2 square feet with no bad reports.

Of course you can by using a crossover. Are you not using any kind of crossover? My Peaveys are band passed from 80 Hz to 3500 Hz so they only play midbass/midrange. Whether you want bass or midrange out of them, they will need the proper crossover because playing full range, they will not sound good.

My HU has sub out. But the cutoff isn't adjustable and I still heard allot of mids from the 1505 compared to the fosgate 10". I do need a new HU but haven't researched which.